She's confused and idk what to do

Pls take a few mins to read what happened, very short and simple.

Hello guys, I'm 23 years old. Recently i met this 19 year old chick on tinder 3 weeks ago, people tend to use this app for many different things so i won't judge. We been talking for 3 weeks, we even facetimed eachother, the first week we used to listen to music on the phone and talk about different genres, and we would talk for hours and hours non-stop about everything during the first two weeks, lots of fun, laughs, etc. One thing about this girl that i liked was that she was so different compared to other matches i had on this app, she even agreed the same thing with me when we spoke about it. The first day we met around the first week, it was a saturday, she came to my apartment, we went out in my car to a restaurant and i bought lunch and we ate, after that we came back to my apartment and saw a movie, the next day she came again we did the same thing but this time we lay down in my bed but didnt hug or anything until i was holding her hands and things got awkward, well, at that moment she didn't care much about it, she started smiling and let me kiss her, things got pretty crazy and we had sex, everything went smoothly well, she even told me she felt so nice around me, and that i make her feel happy. At the end of that day she left and called me saying that she already misses me, we started talking even more than before on the phone, we started talking about being in a serious relationship, and moving in together, she agreed. She even said she had sex with me the first day, due to the way i treated her in the beginning, she called me a unique man, and that she never felt treated that way by a man and that the confidence i had went speaking with her in person was priceless. We would sleep on the phone together, talk about how we miss eachother already and how she loves being w me. We were basically in this love movie and we couldn't get out of it. Alright, those two weeks were 100% ok, everything pretty unique and fun, we loved it. Everything went good until she started getting distanced, around the third week, less text messages, less calls, less topics, and i seriously didn't know why until i told her to read our chat history and see how things changed so quick, i told her that she changed and she wasn't like before, she told me "I'm sorry, i'm very confused, idk what i want". So right now, i'm leaving her alone and letting her think and realize what she really wants, i barely text her and when i do this she texts me saying she misses me. I really don't understand what to do, i wanna give her attention but i also don't want her to think that i'm a needy man. I'm thinking of asking her out and ask her to be my gf in person but idk, i think she really needs some time to think about it? She once said it was too quick, but i feel like when we don't talk we get more and more distanced. Any advice on what i can do or tell her? Sometimes we overthink too much and we get frustrated, i'm trying to handle everything, but sometimes it makes me think that she only wanted to have some fun with me. She's very good looking and very friendly, and we both have feelings for eachother, i really don't want to lose her. Any advice?

1. She's only 19. 2. It was only two weeks and you started talking about moving in together. I think it was a romantic whirlwind and then reality started to sink in. If she wants to be with you again, she'll let you know. You can't lose someone you never really had.

Give her space, this happens a lot with women at this point. Just be patient. Don't worry about having to win them or prove anything to them.

Snow is right "we started talking about being in a serious relationship, and moving in together"
We - as in YOU probably brought it up.
Don't ask her to be your girlfriend.. it's been two weeks. Don't rush things like that. You will ruin a good thing.
You dont even really know this woman yet.
People can hide who they are for the first 90 days, then their bad habits and more of their natural self comes out.
Moving in..? Really man..

Women will adore you more when you're patient, and give them the space to choose (whether that's you, or not you) and feel free.

You dont want her to think you're needy, but.
"but i feel like when we don't talk we get more and more distanced."
That's a needy sentence in itself. A non-needy man would love to be with them, but ultimately he is content with or without them.
Women can pick up and recognize this stuff easily.
Stop worrying and just concentrate on having fun times.